Nonetheless, Ocasio-Cortez took a lead out of the gate and won by a 57-42 landslide.
Crowley has been in Congress since 1999 and hadn't faced an opponent in a primary election since 2004, when Ocasio-Cortez was just a teenager. If she wins, she will be the youngest person ever elected to Congress.
One of the many new female faces joining USA politics this year, Ms Ocasio-Cortez is a Bronx-born Latina, a community organiser and educator from a working-class background.
Some say the changing demographics of NY voters - and Democratic voters across the USA - will be key in the 2018 midterms.
Unlike the other insurgent candidates, Ocasio-Cortez was able to convince enough voters to vote for a new face instead of a 20-year incumbent.
"I'm an organizer in this community, and I knew living here and being here and seeing and organizing with families here, that it was possible", Ocasio-Cortez after her victory. Earlier this week, Pressley called for defunding the federal Immigration and Customs Enforcement, which she said "is creating an atmosphere of toxic fear and mistrust in immigrant communities". Back when Ocasio-Cortez went by the nickname "Sandy", she had a reputation for being involved and motivated, Sullivan said. That includes charting a vision, she said, for "everyday people trying to make ends meet".
"Not all Democrats are the same", she said in her May campaign video, adding - her voice rising with emotion - that a Democrat who "doesn't send his kids to our schools, doesn't drink our water or breathe our air can not possibly represent us".
Several factors may have allowed Ocasio-Cortez to pull off her upset of Crowley, who had been a candidate to succeed Nancy Pelosi as the party's leader in the House.
"The energy in the Democratic Party is self-avowed socialists, open borders", McConnell said in an interview with Politico on Wednesday. "But after 20 years of the same representation, we have to ask: Who has NY been changing for?"
Tuesday night, Holtzman couldn't help but think of that moment as she watched Alexandria Ocasio-Cortez pull off an equally implausible victory.
Ocasio-Cortez was outspent by an 18-1 margin during her race but won the endorsement of some influential groups on the party's far left, including MoveOn, as well as the actress Cynthia Nixon, who is running for governor. "The fact that in a very progressive district in NY, it went more progressive ... is about that district". Washington, however, is dominated by an army of lobbyists, lawyers, economists and consultants who insist that money in politics always matters more than people.
President Donald Trump blasted Crowley, a fellow Queens native who has been a harsh critic.
"I wouldn't look into this that this is a progressives versus moderates, or a political newcomer versus a long-term incumbent", she told reporters.
District 14 covers parts of the Bronx and Queens, where census numbers show the population is almost half Hispanic - very different from when Crowley first took office 20 years ago, CBS2's Andrea Grymes reported. In districts and states where the Democratic Party holds an overwhelming advantage, the power of ideas can indeed overcome the power of money. Who's the new leader? Ted Kennedy, D-Mass., on immigration issues, but soon turned her attention to the grass-roots work that would come to define her candidacy.